Let me preface by saying I believe this is a marketing ploy and the running world is not ready for a sub 2 marathon.
However, an interesting point to bring up, what is holding us back from sub 2. Nutrition, training, genetics?
Because we already know a human is capable of running 1 mile in 4:34, heck even 13.1 miles in 4:34, but what is stopping the body from continuing that pace for another 13.1 miles.
The limit of the human body not physically capable of the pace is an invalid argument so the limiting factor is what? and Furthermore who as well. ie: The limiting factor for Kipchoge is different than for Desisa, than for Tadese.
Just something to chew on